Effects of Maternal Nicotine Exposure on Laminin Αlpha 5 Expression Change of the Basal Membrane in the Distal Convoluted and Collecting Tubules in Mice

It is obviously approved that Fibronectin and Laminin α-5 (LAMA5) expression will change, in some organs of fetuses that their mothers were smoking during pregnancy period. For example, the expression of mentioned proteins in newborns decreases in parenchyma of their lungs. In present study, we evaluated the effects of maternal nicotine exposure on LAMA5 expression change of the basal membrane in the distal convoluted and collecting tubules in Mice. The present experimental study was performed on 28 pregnant mice which were randomly divided into four groups (n=7). Pregnant mice in experimental day 1 group received 2 mg/kg nicotine from gestation day 7 (GD7) to last day of pregnancy and experimental day 14 group received the same amount of nicotine from GD7 to post natal day 14(GD14). Control groups 3 and 4 were injected with the same volume of normal saline parallel to experimental groups (Con). After the last injection, all the newborns (average 50 newborns in each group), were anesthetized in order to remove their kidneys and become prepared for Immunohistochemical method and real-time polymerase chain reaction to detect the expression of Laminin. Data were analyzed using non-parametric Man-Whitney U test and t-test. Our results show that LAMA5 mRNA expression in the kidneys of newborns treated with nicotine, Exp D1 increased about 2-fold in comparison with Control day 1 group, but decreased in Exp D14 (0.62±0.19) comparing to Control day 14 (0.95±0.14) (p=0.043). Lama5 Immunoreactivity in collecting tubules respectively increased and decreased in the Exp day1 and day 14 groups in comparison with Control groups (p=0.039). In the distal convoluted tubules, only a significant difference was found between the experimental day 1 group and Control day 1 group (p=0.041). Maternal nicotine exposure may induce abnormal Laminin expression as a main component of renal base membrane, which may cause defects in kidney function and structure during life time.